The Annals of Internal Medicine study tracked deaths in the state from 2001 to 2010 and compared the rate to counties in New England with similar demographics. It found that the mortality rate dropped by 3 percent in the four years after the health care expansion, according to The New York Times. Nationwide, if the mortality rate dropped 3 percent, that would amount to 17,000 lives. Areas with poor and previously uninsured individuals benefited the most from health insurance and saw the sharpest decline in deaths.

In other words, Romneycare has made a very strong case that Obamacare will save lives. While this study doesn't definitively prove that access to health insurance improves health — it's possible there was some factor the study didn't account for — it's the most compelling argument yet. "It seems pretty clear that expanding insurance coverage will lead to gains in saving lives," Benjamin Sommers, the Harvard University School of Public Health assistant professor who led the study told Vox's Sarah Kliff. "What I don't think you can argue anymore is that health insurance doesn't matter."

Besides proving that the real world model for Obamacare will possibly save lives, this study also challenges the results of a 2013 study that argued health care doesn't matter. In the New England Journal of Medicine study researchers compared the health of 10,000 Oregonians over 18 months — some won insurance through a state lottery for a limited expansion, and some did not. That study found that insurance didn't make a significant impact in health, something Obamacare detractors pounced on.

This study is more robust — it followed 270,000 people over four years. "The Oregon study is an extremely well-done study, but it's just impossible to randomize several hundred thousand people to coverage and follow them for 4 years," Sommers told Jonathan Cohn at The New Republic. "That's what we can do with the Massachusetts natural experiment, and it gives us much greater ability to identify these sorts of health impacts of insurance coverage.”

This leaves Obamacare detractors with one less-than-ideal argument against health care: how much is a life worth? The Annals study found that, for every 830 people who enrolled in Romneycare, one life was saved. Michael Cannon of the Cato Institute argued on Forbes that works out to $4 million a person, which is too much. Others, including the University of Chicago's Harold Pollack, argued that there are more potential benefits to health insurance than just not dying. Just being alive is a pretty low bar to measure your quality of life. Romneycare made a very strong case that expanding health insurance has tangible benefits, especially to low-income people who might benefit from Medicaid. Now lawmakers have to decide if those lives are worth it.

News reports are focusing on the Germanwings pilot's possible depression, following a familiar script in the wake of mass killings. But the evidence shows violence is extremely rare among the mentally ill.